There are many applications which realize operation and display by utilizing a window system in order to realize a multi-window environment. The window system is a mechanism on a computer and software therefor which allocate unique regions (windows) respectively to a plurality of parallelly-operating tasks (applications) and multiplex screen output, and the window system is widely utilized today. In the window system, basically, the number of the pointer operable on one screen is one. For example, when a plurality of windows are displayed on a large screen and operated by a plurality of operators, a mechanism for carrying out simultaneous operation is required to be mounted separately from the window system.
For example, Patent Literature 1 discloses an electronic meeting system of a multi-window environment having information processing terminals and a shared screen display device which are connected with each other via a network. Patent Literature 1 discloses window controlling rights of the case in which windows on the shared screen display device are simultaneously operated by a plurality of operators by using respective operation terminals.